The existing technology is well-developed in the production of infrared photodiode detectors based on HgCdTe as the sensing material, and a discussion of the requirements for infrared scanning and staring focal plane arrays is contained in the paper by Balcerak, et al., "Mercury cadmium telluride material requirements for infrared systems", J. Vac. Sci Techn. (Aug. 1992), and the paper by Tennant et al., "Key issues in HgCdTe-based focal plane arrays: An industry perspective", J. Vac. Sci Techn. (Aug. 1992).
In addition, the present state-of-the-art is indicated in the paper by Schoolar et al., "Investigation of the generation-recombination currents in HgCdTe midwavelength infrared photodiodes", J. Vac. Sct Techn. (Aug. 1992), and the paper by Arias, et al., "MBE HgCdTe Heterostructure p-on-n planar infrared photodiodes", J. Electronic Materials. Vol. 22, No. 8 (1993). Additional relevant references appear in annual proceedings of the "U.S. Workshop on the physics and chemistry of HgCdTe and other IR materials", published until 1992 in the Journal of Vac. Sci. Techn., and after that, in the Journal of Electronic Materials. All these references indicate that the state-of-the-art is based on double layer HgCdTe heterostructures, either in planar or mesa configurations.
The double layer Hg.sub.1-y Cd.sub.y Te/Hg.sub.1-x Cd.sub.x Te (x&lt;y) heterostructures include two layers of HgCdTe with different compositions, and a CdTe passivation which is problematic in production, as indicated by the above-mentioned references. These heterostructures are technologically complex and costly to fabricate. The currently used CdTe passivation is problematic due to the complex double heterostructures, such as are shown in the prior art illustration of FIG. 1 herein. In particular, the mesa structure further complicates the problems encountered during deposition of the CdTe passivation.
Therefore, it would be desirable to produce a photodiode with a simplified device architecture which benefits from application of the best growth technology for the sensing material, and application of the best growth technology for passivation, without limiting the sensing material to a specific technology, to achieve the requirements of large-scale production.